1. FIELD OF THE INVENTION
This invention relates to a shipping rack convertible to a first rack length for loading onto a semi-trailer and convertible to a second length for loading onto a railroad boxcar.
2. PRIOR ART
Racks of the type, to which the present invention relates, are commonly used for shipping industrial parts. The parts are normally elongated members which do not readily fit into box-like containers. For example, automobile bumpers are elongated and have a curved configuration which does not readily adapt to shipment in box-like containers. The racks used for this purpose normally have a bottom wall and upstanding end walls but no sidewalls. The elements to be shipped can be easily loaded onto the racks with the racks giving vertical and endwise support.
Loaded racks are normally shipped in conventional semi-trailers and railroad boxcars. The semi-trailers referred to are of the type normally pulled by a tractor on highways or, in some cases, shipped for long distances on railroad flat cars.
Both semi-trailers and railroad boxcars have assumed a relatively conventional width. For example, standard railroad boxcars have an interior width of about one hundred ten inches while many semi-trailers have an interior width of about ninety-eight inches. Racks are normally stowed in either railroad boxcars or semi-trailers lengthwise across the width of the railroad boxcar or semi-trailer. There must be a relatively snug fit of the racks across the width of these units so that the racks will not shift within the transporting unit for any appreciable distance while the unit is moving. Such shifting, if it gained momentum by traveling a foot or so within the transporting unit, could cause severe damage to the unit possibly rupturing the sidewalls and/or to the goods carried by the racks. It is, however, desired to have a small clearance between the ends of the racks and the sidewalls of the transporting unit, to facilitate loading and unloading and also to accommodate the small discrepancies in standard width which are encountered in practice. Two inches is normally considered adequate clearance.
In the past, different shipping racks have sometimes been utilized for semi-trailers and for railroad box cars. More recently, advances in the art have allowed the use of one shipping rack in both applications by utilizing pivotal rack extension assemblies. These rack extensions adapt the length of the shipping rack to either the rail car width or the semi-trailer width to allow the shipping rack to be used in either application. An example of such a construction is set forth in U.S. Pat. No. 4,699,280 to Hoss.
While this type of shipping rack has increased the efficiency and convenience of shipping parts by use of these racks, other problems have been incident to the use of these racks. A shipping rack, such as that disclosed in the above U.S. Pat. No. 4,699,280, has rack extension arms which are either locked in the extended position (for use in railroad boxcars) or in the retracted position (for use in semi-trailers). It has become a problem in that during forklift loading or unloading of the shipping racks onto or off of railroad boxcars damage may occur to the extension arms because they are vulnerable in the extended positions. This may be due to the difficulties in controlling forklifts in general or to errant operation of the forklift, but in any case the extensions are often broken or bent requiring repair or replacement of the extension arms, which is costly in both repair costs and down time.
It has therefore been a goal in the art to find a construction which would utilize a shipping rack having rack extensions without being subject to unnecessary repair or down time caused by such inaccurate loading and unloading of the shipping rack.